Calendly slowing website, because of script

Question

After integrating Calendly into my website caused a decrease of page speed.

The first thing, I tried was to add async and defer at the end of script

<script type="text/javascript" src="https://assets.calendly.com/assets/external/widget.js" defer></script>

But it doesn't improve speed, so what should I do to improve the speed of page?

Answer 1

So I have done it with javascript, and It improved speed from 40 to 80 points. Basically that loads Calendly after a few seconds, so It doesn't slow the page at the beginning.

window.onload = function() {
 window.setTimeout(function () { 
  var script = document.createElement('script');
  script.async = true;
  script.src = 'https://assets.calendly.com/assets/external/widget.js';
  document.querySelector('head').appendChild(script);
 }, 3000);
};